This invention relates to an apparatus for positioning the back and trunk in a sitting position and then measuring the shape of the back and trunk when so positioned.
Body-supporting seats are especially important to persons with neuro-muscular disorders and physical deformities who must be seated for long periods of time. Therefore, customized, comfortable and usable seating is of special value for these persons and such seating must provide suitable positioning and support.
A common present technique for providing a customized shape is based on a dilatency casting technique, where the impression of a person's shape is obtained with a "bean bag" and a vacuum drawn on the bean bag to maintain the "beans" in the position to which they have been impressed. A plaster cast is formed over the contour of the vacuum bag, which is used to form a positive mold. This mold is subsequently used to fabricate a support surface, such as a brace, seat, seat back, etc. This technique obscures the individual and makes it difficult to determine the state of posture or to control the posture while the impression is taken. Other techniques for providing a customized back and trunk seating arrangement have also been used.
The present invention includes an array of positioning fixtures that provide complete flexibility in positioning an individual and maintaining a desired posture. The invention then enables the determination of complex three-dimensional contours of the individual's body surface, and provides an accurate, inexpensive and quick assessment and determination of the contours to enable the subsequent fabrication of the customized body support. The invention has an additional application as a diagnostic instrument to determine anomalous contours and spinal deformities.
The shape sensed by the invention can be stored to determine changes resulting from growth, progression of a pathology, pre- and post-interventions, etc. The invention provides the capability of positioning and holding an individual in a prescription posture where the surface contour of the posterior trunk may be determined.
The positioning is accomplished with an array of adjustable pads arranged in rows, and the apparatus has a total of five degrees of freedom. These include: tilt adjustment of the frame to establish the back plane; vertical adjustment of the positioning pad by rows; individual lateral and depth adjustments of individual pads; and rotation of the pads individually about a vertical axis.
The shape sensing is accomplished by tracing a transverse cross-section of the posture half of the trunk at serial increments along the vertical axis of the trunk. The tracing is based on the angular orientation, linear displacement, and vertical elevation of a radial arm. The frequency of data points is arbitrary. More or fewer points can be measured according to the severity of the curvature within a particular region.
Once the shape has been determined, this information can be used to produce a customized back and trunk support for the individual. One way of doing this which may be used with the present invention would be by digitizing the shape sensed by the electromechanical transducer of the present invention using an analog-to-digital converter, and enter the information into a digital computer. The computer can be used to control a continuous numerical control (CNC) three-axis milling machine for carving the contour of the back and trunk directly into a material of choice, similar to that shown in the co-pending application of Brubaker et al. for making seat cushions (entitled CUSTOM CONTOURED WHEELCHAIR SEAT AND OTHER BODY SUPPORTS, filed Mar. 9, 1989, U.S. Ser. No. 07/320,959) and now abandoned which was split into U.S. Ser. No. 07/652,442 filed Feb. 6, 1991 as a file rapper continuation application and U.S. Ser. No. 07/633,056 filed Dec. 24, 1990 as a divisional application and now abandoned. Pending U.S. Ser. No. 07/652,442 is incorporated herein by reference.
For a better understanding of the nature of the present invention, reference should be had to the accompanying drawings and the detailed description below.